Hi again Lindoz,
If you save the midis as technics sequencer you save a lot of space, 400 midis are around 16 MB but it depends how you format the card. SD is cheap now anyway compared to a year ago. Get a big card and you can put audio on from the Motif if you still have it
No usb possible, neither is a host, and the sx6 usb never got drivers. Back up your sx6 partition through Techmanager and restore it direct to SD card with the free MDBC program.
Ordinary midi lyrics will play on the 7k as technics sequencer files, or you can just make jpgs or bmps of text files and play lyrics as a slideshow.